I'll just copy+paste my post from there. Be forewarned, it has comments about PvE too!

List your primary talent tree(s), i.e. Holy/Disc. Everything.

I have full tier6 shadow gear, full tier6 non-set healing gear, 3pc season3+2pc season2 shadow arena gear plus all honor epics, and full season2 healing arena gear with a mix of season2 and 3 honor epics. List the content you're primarily pursuing or most enjoy, i.e. Raiding, PvP, Solo, etc... I do it all and pursue all aspects at a high level (min/maxing), but I'd say I enjoy small group (<=5 players per side) PvP most. Provide a brief description of the areas you feel are most in need of improvement (you may list a maximum of three issues and each issue should be described in one or two sentences).

PvP - Survivability and Mobility
Most priest PvP survivability issues (for any spec) stem from a lack of any ability to prevent damage from physical dps classes with absolutely no counter to melee snares and more melee fear breaks than you can shake a stick at. Some sort of snare/stun/root removal tool, possibly on a medium-to-long cooldown is in order (Stoneform is an excellent example, but it only works on rogues and only dwarves get it).
Edit: Priests do NOT need increased survivability. They need to have more uniform survivability against different class types. It's a bit too much rock/paper/scissors at the moment.

PvP Shadow - Longevity
In addition to the survivability and mobility issue, shadow suffers from severe mana issues in competitive PvP. In PvE, our longevity comes from VT being permanently applied to our target, and it appears that our mana efficiency is balanced with that assumption; making VT "stick" in PvP as well seems like the logical solution, as well as a reduction to dispel's mana cost through a deep shadow talent.

PvE Healing - Raid Stackability
Healing priests do not stack beyond the first as well as other healing classes on raids. We have the most tools to keep someone alive in any number of situations and are the most fun to play of any of the healers, but an equally skilled and geared player on a shaman or paladin can keep people alive just as well while providing a significant passive benefit to other aspects of the raid.

List up to five specific spells/abilities/talents you feel most need change, redesign or improvement in the order you feel each is most in need of attention. (MOST to LESS)

Vampiric Touch in PvE
Vampiric Touch (+ Vampiric Embrace, but mostly VT) is too good in PvE. Shadow priest damage should not be as competitive as it is if the mana (and health) return remains as-is and continues to scale as it does. Any nerf to mana returns, however, needs to be coupled with an increase in personal mana efficiency for the shadow priest; we already have to chain-chug pots so our group doesn't have to, and that's without a nerf.

SW:P+VT (shadow dots) in PvP
Both cost too much mana to constantly refresh, and are thus penalized too severely against defensive dispels. Shadow priests are completely reliant on VT being active for any reasonable amount of longevity (try playing a shadow priest in PvE seriously without VT up, let me know how that goes), so making VT (but not SW:P) difficult or impossible to remove seems appropriate.

Silence
The unreliability of this spell against classes with a silence resistance talent and shadow's dependence on it landing successfully in competitive PvP coupled with the 45 second cooldown could use some work. A possible shorter silence duration and lowered cooldown similar to the counterspell and spell lock changes would be good (the resistance chance also reminds me of the old improved concentration aura and talisman of the breaker).

Shadow Resilience
Magical damage mitigation is the last thing I worry about as a priest regardless of my spec, especially considering that shadow's other defensive tools actually work on casters ( they're not fear immune warriors, undead rogues, and BM hunters, and we have chastise to interrupt a spell cast, and of course silence). This talent also does not provide enough benefit per point given the alternatives at that tier in the tree.

Silent Resolve
Talents like this and stoicism for paladin, as well as junk buffs like blessed recovery, serve no purpose other than to introduce unnecessary levels of randomness in competitive PvP and detract from proper balance and fairness. Silent Resolve also provides very little benefit per talent point.

I didn't have it in my post there because it's really beating a dead horse, but racials are too defining. Chastise + desperate prayer + stoneform is way too good for healing priests relative to the other options, and WOTF + devouring plague is significantly better for a shadow priest (yes DP is dispelled by shamans and priests easily, and removed by stoneform, but it works against teams without a healing priest or a shaman and can be covered with silence/CC to an extent. It's also at least castable in shadowform).

This question in itself is flawed. I play a priest – any top end priest will agree that your spec suits your situation. If I want to PvP, I go disc/holy. If I want to raid heal, I go holy/disc. If I want to dps, I go shadow.

Right now I am focused primarily on PvP (have gotten glad in all three brackets both seasons).I enjoy raiding as well, and as far as progression I have seen up all SSC/TK/Hyjal clear and up to ROS in BT.

Provide a brief description of the areas you feel are most in need of improvement (you may list a maximum of three issues and each issue should be described in one or two sentences).

1) PvP Shadow Longevity – Currently, Shadow Priests are on a very limited time scale for PvP. Their dispels cost a lot of mana, and their spells cost even more. To top it off, Vamp Touch is easily dispelled.

2) PvE Healing compared to other classes- Currently, other classes can do everything better than a priest. A paladin can tank heal better, a shaman can raid heal better (not to mention that we NEED to go 41 holy to even have a shot at raid healing), and a druid can HoT up people better. While it may be argued that we are “jack of all healing,” that assumption is flawed since healers are assigned specific roles in all fights.

3) PvP Survivability against melee classes - A good warrior can absolutely DESTROY a priest with a combination of mace stuns and massive damage. To top it off, out one spell that lets us get away (fear) is completely useless against warriors. Non dwarf priests also have a very hard time against rogues.

List up to five specific spells/abilities/talents you feel most need change, redesign or improvement in the order you feel each is most in need of attention. (MOST to LESS)

1) Vamp touch in PvP – Needs some sort of dispel resistance, or that and SWP should cost less mana.

2) Divine Spirit in Disc. Tree – Currently a priest has to either spec DS or healing. It is very silly that in order to get a mostly PvE buff you have to disregard our only real way to keep up with raid healing (Circle of Healing).

4) Binding Heal – I regret ever even buying this spell at 70. I don’t know anyone who seriously uses this spell in PvE or PvP. Prayer of Mending heals for more against two targets, costs less mana, and is instant.

5) Psychic scream – Should have some effect on warriors to give us a chance to survive. Maybe change it to some sort of disorient effect for less duration.

I am a PvPer who has respecced many, many times, and so as my perspective is independent of spec, I'll critique the class from the point of a player of each tree, from left to right. Hopefully this doesn't merit my post for deletion.

Discipline

Areas Most in Need of Improvement

Focus. It's ironic that the tree with so many talents with "focus" and "power" in their names should be the most ambiguous and flavorless talent tree. You guys have made it clear that you know Discipline is a little lacking in direction, but I'm going to be more specific. Aiming for longevity is great, and targetable Pain Suppression, which helps mitigate burst and increase the chances that the fight will last a very long time to take advantage of the Priest's talents, was a great addition. And while Focused Will was clearly intended to provide an alternative to Blessed Resilience, the fact that its effect isn't decreased by resilience (i.e., -100% crit chance isn't that effective when there's only a 10% chance for you to be critted, regardless of procs on normal hits) and that the Priest receives bonus healing when the Priest is always the target has turned Discipline into the PvP healing tree and Holy into the PvE healing tree. Nobody likes having no choice in spec because one tree is clearly the best.

No new signature ability. Every talent tree becomes way cooler and more fun when you unlock a new, short-cooldown active ability that becomes a routine part of that class's arsenal. In fact, the most innovative and exciting trees are the ones that offer new abilities that put a twist on the class's traditional operation, or that fill a functional hole in class's Spellbook. Mangle is the difference between kitties and lions. Swiftmend is what makes PvP healing possible. Mortal Strike is why Warriors are the essential 5v5 class. Mind Flay becomes a Shadow Priest's staple spell. Unstable Affliction allows Affliction Warlocks to actually deal damage against competent teams. Mutilate and Hemorrhage are some of the most deadly Rogue abilities, both for their damage dealt and combo points generated. Each of these is a signature of their respective specs. Divine Spirit is lame, and Inner Focus, Power Infusion, and Pain Suppression all have relatively lengthy cooldowns. It feels like Reflective Shield is supposed to be the signature, routinely used Discipline spell, as it fundamentally changes how Power Word: Shield operates (dealing 800 or more "free" damage per cast is nothing to laugh at), but Reflective Shield's breaking CC makes it a talent to be avoided at all costs, at least until that bug (which appeared in patch 2.2) is corrected.

Abilities Most in Need of Change

Inner Fire/Improved Inner Fire. Fel Armor increases damage dealt and healing received. Demon Armor increases armor, Shadow resistance, and periodically restores health. Mage Armor increases spell resistance and mana regeneration while casting. Frost Armor increases armor and slows attackers. Molten Armor increases chance to critically strike with spells and reduces chance to be critically hit. Inner Fire increases armor for 20 strikes. If this spell is to be kept only as a relic of Warcraft 3, it should either be balanced to be targetable, and then perhaps by sacrificing some passive self-defense Priests can see a greater return from talents and spells. In lieu of attack power, it could grant some healing received on each attack sustained or just some +damage/healing. Some synergy could be generated based on the spells the Priest is currently casting. Or the spell could simply serve as dispel backlash, causing perhaps an Impact effect (see: first tier of Mage Fire talents) or a Chastise effect.

Martyrdom. Martyrdom needs to be trained. There's no way around this one. It is impossible to function in PvP as a Priest without this ability. If you don't believe me, try it. Seriously.

Enlightenment. With 800 Stamina and 450 Intellect (difficult numbers to achieve without Mark of the Wild + Blessing of Kings), Enlightenment increases Stamina by 40 and Intellect by 22.5. This is an increase of 400 health and 338 mana for a 5-point talent 35 points deep into the tree. For purpose of comparison, many classes see 10-20% spell coefficient increases or +spell damage based on stats. Beast Mastery Hunters and their pets attack 20% faster. Combat Rogues have a 20% chance on off-hand attack to gain 15 energy. Subtlety Rogues gain 15% in Agility. Isn't spreading stats out supposed to be cheaper than stacking one stat? If Rogues gain 15% in Agility, and if Marksmanship Hunters, Enhancement Shamans and Fury Warriors gain 10% in Attack Power, shouldn't Discipline Priests at the very least receive a 10% increase, considering the talent affects 3 separate stats? Enlightenment in its current form sucks.

Reflective Shield. Please fix the (recently introduced) bug that causes this talent to break CC. This talent is worthless in PvE for its negligible effect, and now undesirable for PvP.

Mental Strength. This talent's effectiveness decreases dramatically whenever regeneration is brought into play, which wouldn't be such a big deal if the Discipline tree's current purpose weren't lasting through a long fight. After a Priest has gone OOM and is depending on regeneration (in PvE) or sips of water (in PvP) to keep operating, this talent becomes effectively inactive. This talent also just feels out of place in a tree (and class) that is clearly emphasizing the benefits of regeneration through cost reduction and spirit-based talents.

Mana Burn/Improved Mana Burn. Judging by the necessity of Improved Mana Burn in PvP, Priests are apparently balanced under the assumption that most Mana Burn casts are going to take either 2 seconds or 3, because it is absurd to consider PvPing without this talent, and it is absurd the rate at which Priests can remove mana. Priests are not focused as a damage target in PvP because of their healing ability. Priests are not focused in PvP because of their dispel abilities. Priests are not even focused in PvP because of their fragility. Priests are focused in PvP because of how a Priest can eliminate 10,000 mana in 20 seconds. As is clear from how some of the top-ranked arena teams are setup, mana draining is a popular and effective, reliable tactic. Without a doubt, a player should see significant return for choosing to drain mana instead of performing a more significant action like CC, damage, or healing, but mana draining is, realistically, CC. If Priests in PvP are to be balanced around having a 2-second Mana Burn, please either make it standard an eliminate the talent, or just eliminate the talent so that 17 points in Discipline isn't a prerequisite for entering a battleground or arena, and then Priests can be strengthened in other areas so their preeminent role in PvP, regardless of spec, is something other than finding a Paladin to Burn.

Provide a brief description of the areas you feel are most in need of improvement (you may list a maximum of three issues and each issue should be described in one or two sentences).

1.Mana Longevity- We are by far the weakest of the four healers in terms of mana issues; we are extremely reliant on secondary healers and are undesirable as main healers in long matches.

2.Crowd Control-Our one cc is extremely outdated. The fear itself is not bad, but the 30(27 or 24) second cooldown is not adequate against today's techniques of breaking fear.

3. Mobility-Blessing of freedom/protection and the pvp trinket are the only two ways to break hamstring. Both cost significantly more to apply than a mere global cooldown and ten rage or twenty energy that hamstring and shiv cost to reapply, making us very vulnerable to being snared indefinitely.

List up to five specific spells/abilities/talents you feel most need change, redesign or improvement in the order you feel each is most in need of attention. (MOST to LESS)

1. Inner Fire- This spell is simply outdated. The armor value needs to increase to match the pre-TBC value of mitigation. I would suggest redesigning the spell in the following way:

Make inner fire cost zero mana(see: water shield), last 1-2 minutes(test for balance), remove the element of charges, give it a 10 or 15 second cooldown(test for balance), and make it remove all snare effects(hamstring, crippling poison, entangling roots, frost bolt). This spell redesign would help priests gain advantage against their big weakness: mobility, as well as modernizing the spell.

2. Dispel Magic-This is a root pvp priest ability; priests easily spend 3-4k mana on this spell in arena matches. Currently, many classes have talents that counter dispel magic with resist chances(ie stoicism, silent resolve subtlety contagion). I would like to see a new talent(perhaps deep in the discipline tree) that restores mana for every Dispel Magic that fails/resists to dispel anything. This would not overly affect the dispel resist talents that other classes have; but rather the mana issues that priests face in arena.

I.E. "Recovery(3 ranks)- Chance to restore the mana cost of your Dispel Magic if it resists by 33/66/100%"

3. Psychic Scream- This crowd control is outdated and needs to a) be removed or changed to a horror effect(like death coil), with a 3 minute cooldown. However, instead(or in addition) to this ability, we should have a new spell, "Sleep":

"Sleep150 Mana30 yd range1.5 sec castPuts the enemy target to sleep for up to 10 sec. Any damage caused will awaken the target. Only one target can be asleep at a time. While sleeping, the target regenerates* very quickly. Only works on Humanoids. Cannot be used on mind controlled targets."

This spell would finally give priests a reliable crowd control ability, though with a powerful enough side effect(massive regeneration) that randomly using this ability would actually be detrimental. The regeneration would work to mana as polymorph works, and act as a counter to blindly sleeping everyone. I added the mind control part so this ability would not be abused in PvE.

Overall I believe these three changes would help balance priests in line with other healers tremendously in arena pvp, without making them the premier healer of arena combat.

Provide a brief description of the areas you feel are most in need of improvement (you may list a maximum of three issues and each issue should be described in one or two sentences).

For the most part, I think Disc/Holy is one of the most complete specs in all of WoW with the new PS changes it's a great spec and the best for all 3 brackets atm. So I'll hit on Shadow because it seems that it's the most in need of spec atm.

Mobility: I find myself tanking EVERYONE because of a shadowpriest's lack of movement and the ability of one to just lock them down. Not to mention more than half of our main attacks are castable and shut down by a rogue pretty easily. A shadowfury would be incredibly for shadowpriests, giving us an AoE and a escape would be huge.

Survivability:Impossible for shadow to reduce any damage coming at them. VE is nice, but easily dispelled and you have to wait too long to put it back up. 15% melee reduction is fine, it's the magic damage that gets me.

Dispel Protection: Currently I have to be paired with a lock to avoid getting everything dispelled. My dispell protection is shadow vulnerability which is nice for a pally, but useless for a priest I'd like some way that maybe heals everyone in the party if they dispell the magic debuff.

Buff imp innerfire(30% of your total armor? I dunno just change the talent or the spell in general), buff silent resolve(30% dispel protection). Other classes talents are atleast 50% better for their respective talents.

Nerf mana regen from vt to 4% this spell is to powerful for raid. Nerf felhunter to 10s dispel(comon this thing autofucks us). And for god sakes do something to druid's in 2v2 before I reroll one because they out mana efficiency everyone, why does all their pvp gear have tons of mp5 on it?

Change it so when i target someone and use my pet the pet actually goes after the target instead of often trying to run 100y away at another target.

Occasionally missing on fear when i'm apparently on top of them and reflective breaking cc is also annoying.

Abolish poison... or maybe a slight resistance against poisons. A team with a hunter drains a non-dwarf priest with too much ease. A excellent rogue can beat a priest every time (poisons play a huge roll in that.)

Change shadowfiend... either make the shadowfiend cast spells instead of physical attacks (which will be counted as physical?) so it wont have to run all over the arena to finally return me 200 mana total, or make it actually stay on the target i told him to stay on, regardless of CC's on it, so probably make shadowfiend not able to break CC's, not like he does so much dmg anyway...
Basically the only thing that bothers me atm is the shadowfiend, i would love to get abolish poison but i know that we will never get that =]

Survivability against melee due mobility issues - sure we can tank them for awhile, but armor pen, mace stuns, lolstunlocks, hamstring/imp hammy and intercept stuns with constant ms/poisons is pretty sad when warrs have virtually perma immunity to our only viable cc and rogues can clos to delay/prevent just about every 2nd fear.

Mana regen - the buff we got a few months ago was great but our regen still sucks compared to other classes and tbh, druids just make me want to cry or smash something. Shadowfiend is great in theory, but often it just stands there even though i've told it to attack, warrs can one-shot it, druids can root/outrun it and locks/lock pets are a waste of time as targets because of the shadow resistance.

Spells/Abilities/Talents most in need of change:

1. Psychic scream - usless against warrs, not much better against rogues with half a brain and broken when your fear target pushes up against a wall/pole corner etc even though they are in los and range of you.

2. Inner fire - the armor pen melee now has through gear/enchants means the scaling of this buff needs to be reviewed to have much value.

3. Divine spirit - why hasnt this been moved to the trainer - seriously.

4. Shackle - c'mon let us use this in pvp. Some way, any way.

5. I WISH - abolish poison (ok they wont give it to us, but I can dream).